A microvalve is already known from O'CONNER U.S. Pat. No. 4,581,624 and British Patent Disclosure GB 21 55 152-A. This microvalve is constructed in accordance with multi-layer structure technology known from the semiconductor technology. This micro-mechanical valve essentially has three layers, of which one is a support layer of silicon in which an inlet port and an outlet port as well as a valve seat are embodied. An intermediate layer follows the support layer and an outer cover layer follows the latter, these layers forming a chamber which provides the pressure medium connection between the two connectors.
In this microvalve the cover layer is also formed as a diaphragm into which a closing member, which is associated with the valve seat, is also integrated. An electrostatic operating device is additionally disposed on the diaphragm, by means of which the valve can be opened in that the closing member is displaced vertically in respect to the layer levels while the diaphragm is deformed. Closing of the valve is provided by the restoring force of the diaphragm, under the influence of which the closing member again comes to rest on the valve seat once the operating device is shut off. Thus the electrostatic operating device must overcome the force of the resilient diaphragm in addition to the pressure of the fluid present at the inlet. The construction of this microvalve, which does not compensate the pressure, requires extensive operating devices, because relatively large control forces are necessary.